US2527937A

US2527937A - Hot-air furnace

Info

Publication number: US2527937A
Application number: US43497A
Authority: US
Inventors: Ferdinand H Klug
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-08-10
Filing date: 1948-08-10
Publication date: 1950-10-31
Anticipated expiration: 1967-10-31

Description

Oct. 3l, 1950 F, H, KLUG 2,527,937

HOT-AIR FURNACE Filed Aug. 1o,v 1948 2 Smeets-sheet 1 IN V EN TOR.

Oct. 3l, 1950 F. H. KLUG 2,527,937

HOT-AIR FURNACE Filed Aug. l0, 1948 2 Sheets-Sheet 2 INVENTOR.

Patented Oct. 31, 1950 OFFICE.. l

'HOT-AIR FURNACE Ferdinand H. Klug, BentonHarlior,V Mich.

Application August 10, 1948, SerialNo. 43,497'

This invention relates to improvements .in hot air. furnace. y

The principal objects of. this invention are:

First, to provide a furnace for dcvJmesticuse having increased eiciency and rapid heat transfer characteristics.

Second, to provide a furnace having a lire tube heat exchanger which iseasily cleaned so that the furnace may be maintained at peak operat- I ing efficiency without tearing down the furnace-` or.V employing specialized Workmen.

Third, to provide a furnace with a horizontal re tube heat exchanger which is easily assembled as a unit on the remainder of thel furnace and which employs the principle of counterflow of the hot gasesv and the air being heated. f

Fourth, to. provide a furnace with a refractory.

combustion chamber which functions to store heat for hold-over heating between operating periods of the burner and which at thesame time` does not materially obstruct the rapid passageofheat from the burnerk to the heat exchange surface.

Fifth, to provide a furnace having a divided 'i path of flow for the air beingheated whereby part of the air is heated directly from the walls of the re chamber and part of the air is heated from a' re tube heat exchanger.

Other objects and advantages relating to details of my furnace will be apparent from a consideration of the following description andattached drawings. The inventionY isV further pointed out in the claims.

The drawings, of which thereare two sheetsy illustrate two forms of my furnace.

Fig. 1 is aside elevational view, partially broken away in vertical longitudinal cross sec-- tion, of a rst form of my furnace.

Fig. 2 is a transverse vertical cross sectionalview taken along the plane of the linev 2-.2 of

Fig. 6 isy an enlarged` detailedfcross sectional:

. f 2 view taken along the plane ofthe line {if-6. in

Fig. 7 is a verticallongitudinal cross .sectional view through a second form ofY my furnace.v

`My. furnace. consists generally of an upstanding rectangular fire' chamber l havingthe horizontally extending rectangularheat exchanger 2r extending from the upper yportion of the rear wall' thereof. bustion chamber 3 consisting of perforated `lire brick:l lor.` other refractory material. A burner such as the gun type` oil burner 4 has its mouth arranged through the front wall of the fire chamber and` combustion chamber to produce a llame within the combustion chamber. If desired, a gasburnercan be substituted for the oil burner 4; The'fire. chamber Il and heat exchanger 2 are enclosed in aV suitable generally rectangular casing 5:, .the walls of which are spaced from all walls of the lire chamber and heat exchanger excepting the' rear wall4 of the heat exchanger. The casing 5 andi heat exchangerZ dene a plenum chamber 6 in the rear of the furnace and a cold airlreturn ductl is 'connected' through thefblower; 8rt'oV dischargev cold air into the plenum cham-l ber... A..hot air outletV and stack collar 9 is providedonrth'estop of the casing just over the junction between the heat exchanger and the fire chamber.;

More specifically; the lire chamber lY com'- pris'es a sheet.' of relativelyheavy gauge sheet" I steel folded into rectangular shape and welded as at. I wirr Fig. '31 The-front wall of the fire chamberi's'provi'ded with an observation and clean-out noted'thatthe casing 5 is spaced from the front and side walls of the re chamber l.

v The heat. exchanger 2 consists of a front platev l "l land. rear pla-tell which are connected in spaced parallel relationship-by four longitudinally extending. angle irons I8.

Thef lire. chamber l encloses a com- The plates I6 and I1... denaa plurality of aligned apertures in which the.V ends'of the rertubes I9 are secured. Asis most clearly shownY in Fig. .el the iretubes are sealed to-the plates' t6- and I1' by upsetting the ends of L theftubestof'orm'-theannular beads 20 which aref: sealed against the inside surfacesV of thepl'atesff: .'I'heeentlslY of! the,Vv tubes outside of .the plates; are?.

' front plate IE of the heat exchanger.

then spun or swaged over the edges of the apertures as at 2I.

The flange I5 around the opening I4 in the fire chamber is providedwith a series of studs 22 which are welded to the fire chamber and project rearwardly through holes provided therefor in the The periphery of the plate I6 is rearwardly oifset as at 23 so that a sealing compound 24 can be positioned around the joint between the fire chamber and the heat exchanger. Nuts 25 clamp the heat exchanger to the re chamber.

After the front plate I6 has been bolted to the re chamber a rectangular sleeve 26 is slid over the angle irons I8 to enclose the re tubes I9 and complete the heat exchanger. The rear end of the heat exchanger is supported from the floor by a pair of posts 21. It will be noted that the sleeve 26 extends rearwardly beyond the rear plate I'I of the heat exchanger and beyond the rear Wall of the casing 5 (see Fig. 4).

`In order to separate the plenum chamber 6' from the upper portion of the casing 5, the lower side edges of the sleeve 26 are provided with baille plates 28 which extend laterally to the side walls of the casing 5. The forward ends of -the baille plates 28, adjacent to the rear wall of the nre chamber I, are provided with depending vertical baflles 29 which support the vertically adjustable damper plates 30 for regulating the opening between the plenum 6 and the forward portion of the casing 5 around the re chamber.

The rear end of the heat exchanger sleeve 26, which projects from the rear of the casing, is secured by the folded lapped joint 3| (see Fig. 4) to a rectangular smoke box 32. The smoke box is provided with a collar for attachment to the smoke pipe 33 and is further provided with a clean-out door 34 positioned at the bottom of wa-rdly through the cold air duct 'I by the blower 8 will be forced into the plenum chamber 6 from where part of the air can pass forwardly through the openings 35 underneath the damper plates 3U to around the sides of the re chamber I. Here the air will be heated and forced upwardly through the stack collar 9. The rest of the air entering the plenum chamber will be forced through an opening 38 formed at the rear of the bottom wall of the sleeve 26. From the rear of vthe heat ex-` changer the a-ir is forced upwardly and forwardly opposite to the direction of the flow of the hot gases through the lire tubes, and isdischarged from the heat exchanger through the upper opening 3l adjacent to the stack collar 9. Thus part ofthe air will be heated by the relatively hot walls of Vtheiire chamber while the remaining portion ofthe air will be heated by the relatively cooler `iretubes I5. The proportion of air passing over the two possible routes may be varied by adjusting the damper plates 38. Attention is invited to the fact that the inspection door I3 is positioneddirectly in front of the fire tubes I9 so that it is a simple matter for the householder to push a long handle brush directly through each offthe nre "tubes to force any soot which may have 4 collected therein into the smoke box 32. The soot will fall to the bottom of the smoke box where it is easily removed through the clean-out door 34. It is thus easy to keep the furnace in clean efficient operating condition.

In the modified form of the furnace illustrated in Fig. 7, the fire chamber I, combustion chamber 3, and burner 4 are the same as in the first form of the furnace. The heat exchanger 2A is different from the first form of heat exchanger in that it is provided with an intermediate partition plate 38 which divides the heat exchanger into two sections. The rear section of the heat exchanger is provided with an inlet collar 39 to which the cold air duct 'IA is connected. In this case the duct 'IA extends downwardly through the top wall of the casing 5A. The bottom wall of the sleeve 26A defines an opening 40, opening into the rear portion of the plenum chamber 6A. The plenum chamber is also divided into front and rear sections'by the partition plate 4I and the blower 8 is positioned in the rear section of the plenum chamber to discharge through the partition plate 4I into'the forward section of the plenum chamber. From the forward section of the plenum chamber, air can pass either forwardly around 'the're chamber as in the first form of the furnace,l or upwardly through an inlet opening 36A' inthe' bottom of the heat ex-fl I have thus described two highly practical forms of my furnace which are very efficient inI operation and which materially reduce vthe temperature of the exhaust gases escaping up the chimney due to more complete transfer of heat from the gases to the air being heated. The elements of the furnaceare easily fabricated and assembled and the'furnace is Very easy to keep clean.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. A furnace'comprising a generally rectangular casing having a hot air outlet inthe top thereof, walls forming an upstanding rectangular sheet metal re chamber positioned in the front of said casing and spaced from the walls thereof,

the rear wall of said rire chamber defining an Y opening in the'upper `portion thereof, a heat ex changer comprising Afront and rear plates with a plurality of fire tubes supported therebetween and extending therethrough, the front plate of said heat exchanger being secured to the rear wall of saidre chamber and over said opening,y

the rear plate of said heat Vexchanger forming a and the sides of said casing and cooperating with' the bottom of said sleeve to form the top of a plenum chamber in the bottom of said casing,` adjustable damper plates positioned between the sides of said casing and the rear wall of said Ifire chamber and extendingupwardly tosaid baille plates and arranged' to control the ilo'w offair inlet opening from said plenum chamber in the` rear portion of its lower wall and an outlet opening to within the top of said casing in the forward portion of its top wall, means forming a combustion chamber of perforated refractory material positioned in said re chamber and spaced from the walls thereof, and a burner provided with a tube for projecting a name into said combustion chamber.

2. A furnace comprising a casing having a hot air outlet in the top thereof, walls forming an upstanding sheet metal re chamber positioned in the front of said casing and spaced from the Walls thereof, the rear wall of said fire chamber defining an opening in the upper portion thereof, a heat exchanger comprising front and rear plates with a plurality of re tubes supported therebetween and extending therethrough, the front plate of said heat exchanger being secured to the rear wall of said re chamber and over said opening, the rear plate of said heat exchanger forming a portion of the rear wall of said casing, longitudinal bars connecting the corners of said plates, a sleeve positioned around said bars and enclosing said heat exchanger, baffle plates extending between the sides of said sleeve and the sides of said casing and cooperating with the bottom of said sleeve to form the top of a plenum chamber in the bottom of said casing, damper plates positioned between the sides of said casing and the rear wall of Said fire chamber and extending upwardly to said bale plates and arranged to control the fiow of air from said plenum chamber to the space surrounding said fire chamber, a smoke box secured to the rear end of said sleeve and having a cleanout door positioned in the lower portion of said box, means for delivering air to said plenum chamber, said sleeve defining an inlet opening from said plenum chamber in its lower wall and an outlet opening to within the top of said casing in the forward portion of its top wall, means forming a combustion chamber of perforated refractory material positioned in said fire chamber and spaced from the walls thereof, and a burner arranged to provide a flame in said combustion chamber.

3. A furnace comprising a generally rectangular casing having a hot air outlet in the upper portion thereof, walls forming an upstanding sheet metal fire chamber positioned in the front of said casing and spaced from the walls thereof, the rear wall of said re chamber defining an opening in the upper portion thereof, a heat exchanger comprising front and rear plates with a plurality of fire tubes extending therebetween the front plate of said heat exchanger being secured to the rear wall of said fire chamber and over said opening, the rear plate of said heat exchanger forming a portion of the rear wall of said casing, longitudinal bars connecting the corners of said plates, a rectangular sleeve positioned around said bars and enclosing said heat exchanger, baiile plates extending between the sides of said sleeve and the sides of said casing and cooperating with the bottom of said sleeve to form the top of a plenum chamber in the bottom of said casing, damper plates positioned between the sides of said casing and the rear wall of said fire chamber below said baffle plates and arranged to control the flow of air from said plenum chamber to the space surrounding said fire chamber, a smoke box secured to the rear end of said heat exchanger and having a cleanout door positioned in the lower portion of said box, means for delivering air to said plenum chamber,

said sleeve defining an inlet opening from saidv plenum chamber in its lower wall and an outlet opening to within the top of said casing in its top wall forwardly of said inlet opening, and a burner for developing a flame in said nre chamber.

4. A furnace comprising a casing having a hot air outlet in the upper portion thereof, walls forming an upstanding sheet metal re chamber positioned in the front of said casing and spaced from the walls thereof, the rear wall of said fire chamber defining an opening in the upper portion thereof, a heat exchanger comprising front and rear plates with a plurality of horizontal fire tubes extending therebetween and opening therethrough, the front plate of said heat exchanger being secured to the rear wall of said re chamber and over said opening, a rectangular sleeve enclosing said heat exchanger, baflle plates extending between the sides of said sleeve and the sides of said casing and cooperating with the bottom of said sleeve to form thetop yof a plenum chamber in the bottom of said casing, means for delivering air to said plenum chamber, said sleeve defining an inlet opening from Asaid plenum chamber in its lower wall and an outlet opening to within the top of said casing in its top wall forwardly of said inlet opening, and a burner for developing a flame in said fire chamber.

5. A furnace comprising a casing having a hot air outlet in the top thereof, walls forming an upstanding sheet metal fire chamber positioned v in the front of said casing and spaced from the walls thereof, `a heat exchanger in said casing comprising a plurality of' re tubes secured at their front to the rear wall of said re chamber and communicating with said flre chamber, a sleeve positioned around and enclosing said heat exchanger, baffle plates extending between the sides of said sleeve and the sides of said casing and cooperating with the bottom of said sleeve to form the top of a plenum chamber in the bottom of said casing, means for delivering air to said plenum chamber, said sleeve defining an inlet opening from said plenum chamber in the rear portion of its lower wall and an outlet opening to within the top of said casing in the forward portion of its top wall, and a burner for developing a name in said fire chamber.

FERDINAND H. KLUG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS l Mallory Feb. 13, 1940